1. Field of Invention
The present invention relates to capacitor sheets suitable for use in electro-optical devices and other various electronic apparatuses, electro-optical devices with capacitors, flexible substrates, composite build-up substrates, and electronic apparatuses.
2. Description of Related Art
Electro-optical devices, such as liquid crystal panels using liquid crystal as an electro-optical material, are widely used as display devices in place of cathode-ray tubes (CRT) in displays of various information processing apparatuses and liquid crystal televisions. For example, a related art electro-optical device has the following arrangement. Specifically, the related electro-optical device includes an element substrate having pixel electrodes aligned in the form of a matrix and switching elements such as TFTs (Thin Film Transistors) connected to the pixel electrodes, an opposing substrate having a counter electrode opposed to the pixel electrodes, and liquid crystal, i.e., electro-optical material, filled between the two substrates.
With this arrangement, when a scanning signal is supplied to the switching element via a scanning line, the switching element becomes conducting. In this conducting state, when an image signal with a voltage in accordance with a gray level is supplied to the pixel electrode through a data line, a charge in accordance with the voltage of the image signal is accumulated in a liquid crystal layer between the pixel electrode and the counter electrode. When the switching element is turned off after the charge has been accumulated, the accumulated charge in the liquid crystal layer is maintained by the capacitance between the pixel electrode and the counter electrode and by a storage capacitance. Accordingly, when the switching elements are driven so as to control the amount of charge to be accumulated in accordance with the gray level, light is modulated according to each pixel, and the display gray level varies, thus performing gray-scale display.
It is only necessary to accumulate charge in an electrode of each pixel for a partial period of a period for which one screen is displayed. First, a scanning-line drive circuit sequentially selects each scanning line. Second, a data-line drive circuit sequentially selects each data line within the scanning-line selection period. Third, an image signal with a voltage in accordance with a gray level is sampled on the selected data line. As a result, time-division multiplexing driving, in which the scanning line and the data line are shared by a plurality of pixels, is made possible.
Liquid crystal panels have a structure formed by bonding together, with a predetermined gap therebetween, an element substrate having pixel electrodes and an opposing substrate having a counter electrode. The element substrate and the opposing substrate holding therebetween liquid crystal as an electro-optical material. The element substrate and the opposing substrate are amorphous substrates formed of glass or quartz. Recently, technology has been developed for mounting an integrated circuit having a drive circuit on the element substrate by COG (chip on glass) or TAB (Tape Automated Bonding) and for integrally forming the liquid crystal panel and the drive circuit. The integrated circuit is formed by forming the drive circuit on a chip, which is largely formed of single-crystal silicon, and by sealing the chip with resin. A pattern for inputting an image signal from an external device is formed on the element substrate. A flexible tape wire is connected to the pattern.
The drive circuit of the liquid crystal panel requires a capacitor to smooth a power supply voltage and to boost voltage using a charge pumping system. A problem exists with regard to the manner in which the capacitor is mounted. For example, the capacitor can be formed in the interior of a semiconductor chip in the integrated circuit. Since the capacitor occupies a relatively large area of the interior of the integrated circuit, the semiconductor chip increases in size, and hence the semiconductor chip becomes expensive.
With regard to technology to externally attach the capacitor, the capacitor may be formed by a ceramic-type chip capacitor, and the capacitor may be mounted on a flexible tape wire. The flexible tape wire is flexible, whereas the chip capacitor is rigid. Thus, metal fatigue occurs in a joint portion between the flexible tape wire and the chip capacitor. It thus becomes easier for the chip capacitor to fall off the flexible tape wire. Alternatively, the chip capacitor can be mounted on the element substrate.
The chip capacitor is thicker than the integrated circuit, and it is difficult to mount the chip capacitor on the element substrate formed of glass or quartz. When the chip capacitor is forcedly mounted on the element substrate, the chip capacitor easily falls off because of vibrations and because of differences in the thermal spreading coefficient.
In view of the foregoing circumstances, the present invention to provides a capacitor sheet which is inexpensive and which can be mounted stably, an electro-optical device with a capacitor, a flexible substrate, a composite build-up substrate, and an electronic apparatus. The present invention also enhances a light-blocking effect in a non-display region of the electro-optical device.
Exemplary embodiments are discussed below, which address the above problems.
A capacitor sheet in accordance with a first aspect forms a capacitor having a single-layer structure or a multi-layer structure. The capacitor includes a dielectric layer (dielectric film) which is a flexible sheet formed by mixing dielectric material (barium titanate, etc.) powder with a polymeric material polyethylene, resist, etc.) and conductor layers (conductor plates) which are flexible and which are formed so as to hold the dielectric layer therebetween.
An electro-optical device with a capacitor in accordance with a second aspect includes the electro-optical device including a plurality of scanning lines, a plurality of data lines, and pixels (pixel electrodes) arranged in correspondence with intersections of the scanning lines and the data lines and a capacitor sheet as set forth in the first aspect, which is fixed to the electro-optical device.
An electro-optical device in accordance with a third aspect includes the electro-optical device with the capacitor as set forth in the second aspect, and further includes a display region to display information when being irradiated with external irradiation light. The capacitor sheet is mounted along the periphery of the display region, whereby a portion in which the capacitor sheet is mounted is shielded from the irradiation light.
An electro-optical device in accordance with a fourth aspect includes the electro-optical device with the capacitor as set forth the second aspect, such that the capacitor sheet has shock resistance.
A capacitor sheet in accordance with a fifth aspect includes the capacitor sheet as set forth in the first aspect, where the capacitor sheet is formed by a plurality of capacitors formed in each region on a surface of the sheet.
A flexible substrate in accordance with a sixth aspect includes a capacitor sheet as set forth in the first aspect, such that the capacitor sheet is mounted on a top surface of the flexible substrate or is included as a layer in the flexible substrate.
A composite build-up substrate in accordance with a seventh aspect includes a capacitor sheet as set forth in the first aspect, such that the capacitor sheet is mounted on a top surface of the composite build-up substrate or is included as a layer in the composite build-up substrate.
An electronic apparatus in accordance with an eighth aspect includes a capacitor sheet as set forth in the first aspect.